Urban radicals want automobiles banned. Urban moderates can perhaps live with cars as long as they’re neither seen nor heard.

In European central cities the radicals have the upper hand. U.S. cities are increasingly settling for a compromise–an expensive compromise–by putting freeway segments underground and covering them with parkland. Whether called a lid, deck, bridge, or tunnel, there are already at least 24 of these parks in the country and a dozen more somewhere in the planning pipeline. Surprisingly, because of both undulating topographies and the fact that many cities are already operating on multiple above-and-below-ground levels, there are numerous opportunities to construct more freeway deck parks. As the impact of automobiles becomes ever less welcome in cities, these lids have moved from the novel to the accepted to, increasingly, the expected. The sometimes considerable cost has gone from being dismissed as “porkbarrel” to being redefined more positively as amenity investment with high economic payback.

In a study carried out by the Center for City Park Excellence in 2007, it was found that the average size of the nation’s freeway parks is about 8 acres and each covers about 1,600 linear feet of highway. Most famous is Seattle’s aptly named Freeway Park, designed by the Lawrence Halprin firm and opened with great fanfare in 1976, but the concept actually goes back to 1939 when Robert Moses constructed the Franklin D. Roosevelt Expressway along Manhattan’s East River, tunneled it under the mayor’s home at Gracie Mansion and constructed 14-acre Carl Shurz Park on top. In 1950 Moses did it again, in Brooklyn, when citizens rose up against a planned expressway through the center of Brooklyn Heights. As a compromise he added the 1/3-mile long Brooklyn Promenade with its supreme view of lower Manhattan, remarking self-satisfiedly at the ribbon-cutting, “I don’t know of anything quite like this in any city in the world.” The latest have been New Jersey’s innovative highway redesigns in Trenton and Atlantic City and the Rose Kennedy Greenway park blocks over Boston’s massive “Big Dig.”

The Interstate Highway System, when it was originally conceived in the early 1950s, was designed to link but not penetrate cities. By the 1960s, however, the distinction had been forgotten. Highways became the preeminent tool of urban renewal and redesign, and vast swaths of urban real estate were paved over. Waterfronts were blockaded in Portland, Cincinnati, Hartford, Cleveland, Philadelphia, and San Francisco. Nooses of concrete were wound tightly around the downtowns of Dallas and Charlotte. Trenches of noise and smog cut through Boston, Detroit, Seattle, and Atlanta. Stupendous elevated structures threw shadows over Miami and New Orleans. And wide strips of land were taken from large, iconic parks in Los Angeles (Griffith Park), St. Louis (Forest Park), Baltimore (Druid Hill Park), and San Diego (Balboa Park).

A few downtown parks actually survived the devastation thanks to the intervention of historic preservationists, including Lytle Park in Cincinnati and the National Mall in Washington, D.C. In both cases, citizen outcry forced the highway builders to tunnel underneath (although technically Lytle Park was leveled and then reconstructed three years later).

But it wasn’t until the construction of Freeway Park that the “deck the freeway” concept began getting some serious attention. Because of the constrained, hourglass geography of Seattle, Interstate 5 was a particularly damaging road, and the environmentally oriented populace was dismayed by the impact. “There was a large moat of traffic between downtown and historically residential First Hill neighborhood,” says Freeway Park Neighborhood Association President David Brewster. But the city was lucky–not only was I-5 sunk into a deckable trough as it passed downtown, but a former Seattle mayor, James “Dorm” Braman, had just been appointed assistant secretary of transportation for urban systems and the environment by President Richard Nixon. Braman was amenable to the deck, which was promoted by civic leader Jim Ellis and paid for under the city’s “Forward Thrust” bond initiative. Freeway Park opened in time for the bicentennial and garnered coast-to-coast attention. “It was a model for other cities to heal the scar that cuts right through a neighborhood,” says Brewster.

Freeway Park was beautiful and memorable, but it failed on one major count: acoustics. At 5 acres it couldn’t completely muffle the sound of traffic, and the park experience is accompanied by a constant white noise–not obtrusive, but not minimal, either. Phoenix’s 10-acre Hance Park seems to have solved the noise challenge (as has Seattle’s new, much larger Sam Smith Park). Labeled by the Phoenix New Times “a rare Phoenix instance of nature over traffic–in this case, literally,” Hance Park is decked over the Papago Freeway, uniting uptown and downtown and providing a park adjacent to the city’s central library. The freeway (Interstate 10) was originally planned as an elevated bridge through downtown but opposition by citizens and the Arizona Republic killed that idea in a 1973 ballot measure. Not until ten years later did the city finally accept a below-grade solution with the park as a key sweetener. Hance Park opened in 1992 and today is the site of a Japanese Garden. As a sign of success, it is gradually becoming surrounded by a growing number of upscale condominium towers.

By decking over a portion of I-35, Duluth, Minnesota, was able to save its Rose Garden and provide a park connection directly to its Lake Superior. Credit: Minnesota Dept. of Transportation.

Freeway parks have also bridged the divide between cities and their waterfronts. In Duluth, Minnesota, a plan to build Interstate 35 along the Lake Superior shoreline generated intense opposition from environmentalists and historic preservationists. By shortening the planned freeway’s length (and gaining the backing of powerful Duluth then-congressman John Blatnik) the city used the savings to pay for park covers. Ultimately, three different deck parks were built, including one that saved a historic Rose Garden.

Construction costs for deck parks can be wincingly high, but there is also an upside–the land itself is generally free, made available through air rights by the state transportation agency. In center-city locations this can amount to a multimillion-dollar gift. Land near the Santa Ana Freeway by Los Angeles City Hall, for instance, goes for between $2 million and $3 million an acre. In near-downtown San Diego by Balboa Park an acre is worth up to $13 million. Regardless of cost, the actual force driving–and making feasible–most deck parks is the opportunity for neighboring private development and redevelopment. In Trenton, the New Jersey Department of Transportation spent $150 million on the new 6.5-acre Riverwalk deck over U.S. 29, linking the city to the Delaware River. In response, notes Trenton Planning Director Andrew Carten, “The project resulted in a significant spike in interest and the sale prices of property. After all, would you rather look over 600 trucks barreling past every day, or a scenic park and river?” One lot, worth $120,000 preconstruction, was developed with six housing units that sold for $200,000 each. The presence of the park also helped recruit a new 82-unit market rate residential building.

The cost of the Boston Central Artery–the gargantuan project to bury the elevated Fitzgerald Expressway, which yielded as a surface byproduct the Rose Kennedy Greenway–has caused some people to doubt the feasibility of such parks in the future. But the Central Artery was primarily a transportation project that combined massive demolition along with even more massive construction. It also included major bridges and underwater tunnels. Of the $14-billion price tag, only an estimated $40 million was attributable to the mile-long stretch of four parks that opened to the public in October 2008. Certainly not inexpensive, but very much in line with many other new, showcase destination parks that are helping to redefine the nation’s premier urban centers.

The Woodall-Rodgers Park, planned over a three-block stretch of the Woodhall-Rodgers Freeway in Dallas, will connect the currently separated downtown and arts district from the Uptown neighborhood. Credit: Office of James Burnett.

Projects where freeways are already below-grade are more feasible, and four particularly high-prospect opportunities are currently being explored in St. Louis, Cincinnati, Dallas, and San Diego. In St. Louis, Mayor Francis Slay is promoting the “three-block solution,” a plan to cover a portion of I-70 between center city and the world-famous Gateway Arch. “We’re trying to get the annual 3 million visitors to the Arch into downtown St. Louis,” says Peter Sortino, president of the Danforth Foundation, which is handling the planning. “We’re also trying to help those already downtown more easily reach the Arch and the Mississippi riverfront.” An early estimate put the cost at a minimum of $40 million. Cincinnati faces the identical situation. An interstate highway, Fort Washington Way, is a barrier between downtown and the parkland along the Ohio River. Cincinnati had an opportunity to construct a five-block-long park deck during a road reconstruction (and narrowing) in 2007, but shied because of cost. As a compromise, the new Fort Washington Way was equipped with $10 million worth of steel pilings capable of supporting a future park.

Dallas, on the other hand, is plunging ahead with planning and funding a park over a stretch of the Woodall-Rodgers Freeway. The freeway separates the city’s downtown and arts district from the Uptown neighborhood, and a three-block park cover is seen as both improving the urban form and opening up new opportunities for development. A trolley line would run through the park, and condominium towers are expected to flank it on both sides. A developer of a nearby tower is enthusiastic, telling the Dallas Tribune that the park “will be a fabulous amenity to [my] building.” The park’s price tag is estimated at more than $60 million, but Dallas’s confident and ardent boosters are busily raising matching funds from private sources.

Trenton, New Jersey’s new 6.5-acre Riverwalk deck over U.S. 29 links the city to the Delaware River; it is credited with sparking development and reinvestment in nearby properties. Credit: Vollmer & Associates.

In San Diego, downtown interests are in the early stages of evaluating decking a few blocks of I-5 so as to forge a link with Balboa Park. The city has been in the midst of an unprecedented center city residential construction boom, and the highway presents a major barrier for the thousands of apartment dwellers who have little access to green space. Meanwhile, activists in Los Angeles are determined not to lose their “Freeway Capital of the U.S.” moniker and are evaluating eight different sites. “We want to now become the ‘Freeway Deck Park Capital of the World,’” said Don Scott, chair of the Hollywood Central Park Coalition.

Despite the cost of a park deck, there are numerous sources of local, state, and federal funds that can be cobbled together, particularly if an analysis shows that associated development will generate significantly more tax revenue. Often the deck superstructure is paid for by the federal government while actual park development is financed by the city: Phoenix spent $5 million landscaping Hance Park. The Trenton deck came about through reconstruction of a state highway and was paid for by the state of New Jersey. In Cincinnati, 20 percent of the narrowing of Fort Washington Way was financed through private dollars, including $250,000 from the Cincinnati Bengals football team.

7 Responses

Hi Peter, Nice post! I can’t be sure, but I think the first image is actually a lid on I-90 in Mercer Island, which is quite close to Seattle. Freeway Park has really rough board formed concrete, where as those look smoother.

I am excited for and very interested in the opening of Woodall Rogers park here in Dallas. I was working downtown decades ago when the freeway was first built. The added cost of putting it in a “canyon” was controversial at the time, but it is paying off now.

Also, the expansion of the streetcar system is welcome. I’m hoping it can become an integrated part of the transit system and more than simply a tourist attraction.

I wanted to add a little more about Boston’s cental artery example. The Rose Kennedy Greenway is 15 acres spread along 1.5 miles in the heart of Boston and is quite literally a roof garden in some areas. The Rose Kennedy Greenway Conservancy is a non-profit which maintains and programs the greenway, under contract with the State’s transportation agency, which owns the land. More info: http://www.rfkgc.org